DESCRIPTION

The fBwprintffP family of functions is the wide-character equivalent of the
fBprintffP family of functions. It performs formatted output of wide
characters.

The fBwprintffP and fBvwprintffP functions perform wide character output
to fBstdoutfP. fBstdoutfP must not be byte oriented; see function
fBfwidefP for more information.

The fBfwprintffP and fBvfwprintffP functions perform wide character output
to fIstreamfP. fIstreamfP must not be byte oriented; see function
fBfwidefP for more information.

The fBswprintffP and fBvswprintffP functions perform wide character output
to an array of wide characters.
The programmer must ensure that there is room for at least fImaxlenfP wide
characters at fIwcsfP.

These functions are like the fBprintffP, fBvprintffP, fBfprintffP,
fBvfprintffP, fBsprintffP, fBvsprintffP functions except for the
following differences:

(bu

The fIformatfP string is a wide character string.

(bu

The output consists of wide characters, not bytes.

(bu

fBswprintffP and fBvswprintffP take a fImaxlenfP argument,
fBsprintffP and fBvsprintffP do not. (fBsnprintffP and fBvsnprintffP
take a fImaxlenfP argument, but these functions do not return -1 upon
buffer overflow on Linux.)

The treatment of the conversion characters fBcfP and fBsfP is different:

c

If no
l
modifier is present, the
int
argument is converted to a wide character by a call to the
btowc
function, and the resulting wide character is written.
If an
l
modifier is present, the
wint_t
(wide character) argument is written.

s

If no
l
modifier is present: The
``const char *''
argument is expected to be a pointer to an array of character type
(pointer to a string) containing a multibyte character sequence beginning
in the initial shift state. Characters from the array are converted to
wide characters (each by a call to the
mbrtowc
function with a conversion state starting in the initial state before
the first byte). The resulting wide characters are written up to
(but not including) the terminating null wide character. If a precision is
specified, no more wide characters than the number specified are written.
Note that the precision determines the number of
wide characters
written, not the number of
bytes
or
screen positions.
The array must contain a terminating null byte, unless a precision is given
and it is so small that the number of converted wide characters reaches it
before the end of the array is reached. -- If an
l
modifier is present: The
``const wchar_t *''
argument is expected to be a pointer to an array of wide characters.
Wide characters from the array are written up to (but not including) a
terminating null wide character. If a precision is specified, no more than
the number specified are written. The array must contain a terminating null
wide character, unless a precision is given and it is smaller than or equal
to the number of wide characters in the array.

RETURN VALUE

The functions return the number of wide characters written, excluding the
terminating null wide character in case of the functions fBswprintffP and
fBvswprintffP. They return -1 when an error occurs.

CONFORMING TO

ISO/ANSI C, UNIX98

SEE ALSO

NOTES

The behaviour of fBwprintffP et al. depends on the LC_CTYPE category of the
current locale.

If the fIformatfP string contains non-ASCII wide characters, the program
will only work correctly if the LC_CTYPE category of the current locale at
run time is the same as the LC_CTYPE category of the current locale at
compile time. This is because the
wchar_t
representation is platform and locale dependent. (The GNU libc represents
wide characters using their Unicode (ISO-10646) code point, but other
platforms don't do this. Also, the use of ISO C99 universal character names
of the form nnnn does not solve this problem.) Therefore, in
internationalized programs, the fIformatfP string should consist of ASCII
wide characters only, or should be constructed at run time in an
internationalized way (e.g. using
gettext
or
iconv,
followed by
mbstowcs).